Signal distributors are generally used in telephone switching systems to interface high speed electronic central processing units with slower speed electromechanical circuitry. Typically, the signal distributors are connected to the central processor via a bus system, and a signal distributor is selected by the processor transmitting an address over an address bus. The processor then transmits data over a data bus to the signal distributor and the data is gated into the storage registers of the addressed signal distributor. The registers may comprise flip-flops which are set by the high speed pulses transmitted over the data bus. The flip-flops, in turn, may actuate magnetically latching relays and the signal distributor relays transmit DC potentials via distribution points to lines, trunks, and other miscellaneous circuits of the system.
It is desirable to test the signal distributor to verify that all distribution points are functioning properly. This has been accomplished in the prior art through the use of individual scan points associated with each distribution point. The central processor would perform a maintenance routine whereby it would actuate the individual distributor relays while scanning the scan points associated therewith to ascertain if each distribution point had been energized.
While this arrangement is wholly suitable for its intended purpose, it requires a multiplicity of scan points that are used only for test purposes.